"Number Unobtainable" progress tone for the New Zealand telephone system.
This tone is recognized by some switching equipment as SIT and may be
effective against some telemarketers. 4 pulses of 400 Hz, 75 ms each, 100 ms in between, followed by 400 ms silence.
We have four iterations in this recording. Algorithmically generated with dmTS.
This exact sequence is also used to indicate "Number Unavailable" in Guangdong, China.